The present invention relates to an occupant protection system and, more particularly, to an apparatus and method for detecting a vehicle rollover event for use with an actuatable occupant rollover protection device.
To detect a vehicle rollover event, a vehicle may be equipped with one or more sensors that detect vehicle dynamics. The sensors are connected to a controller that evaluates the sensor signals and controls actuation of one or more actuatable devices in response to a determined occurrence of a vehicle rollover event.
U.S. Pat. No. 5,825,284 discloses a vehicle rollover system having an acceleration sensor that provides a signal indicative of lateral acceleration of the vehicle. A processor calculates a roll-moment based on the sensor signal and provides a visual display indicating the likelihood of vehicle rollover.
U.S. Pat. Nos. 5,610,575 and 5,890,084 disclose other approaches to rollover detection.
In accordance with one aspect of the present invention, an apparatus detects a vehicle rollover event. The apparatus includes a rollover sensor sensing vehicle roll and providing a signal indicative of vehicle roll about a front-to-rear axis of the vehicle. A first accelerometer senses vehicle acceleration in a direction offset from the front-to-rear axis of the vehicle up to a maximum acceleration sensing level and provides a first acceleration signal indicative thereof. A second accelerometer senses vehicle acceleration in the offset direction at acceleration levels in excess of the maximum acceleration sensing level of the first accelerometer and provides a second acceleration signal indicative thereof. The apparatus further includes a controller for providing an actuation signal when the signal from the rollover sensor indicates a vehicle rollover condition and at least one of (i) the first acceleration signal indicates vehicle acceleration between a first threshold and said maximum acceleration sensing level, and (ii) the second acceleration signal indicates a vehicle acceleration greater than the maximum acceleration sensing level.
In accordance with another aspect of the present invention, an apparatus detects a rollover condition of a vehicle, the apparatus comprises a rollover sensor securable to the vehicle for sensing vehicle roll and providing a roll signal having a characteristic indicative thereof. An acceleration sensor senses vehicle acceleration in a direction offset from a front-to-rear axis of the vehicle and provides an acceleration signal indicative thereof. The acceleration sensor is capable of sensing vehicle acceleration. The apparatus further includes a controller determining the occurrence of a vehicle rollover condition in response to the roll signal from the rollover sensor indicating a vehicle rollover condition and the sensed acceleration in the offset direction having a value between a first acceleration threshold and a second acceleration threshold.
In accordance with another aspect of the present invention, a method detects a vehicle rollover event comprising the steps of sensing vehicle roll and providing a roll signal indicative of vehicle roll about a front-to-rear axis of the vehicle, sensing vehicle acceleration in a direction offset from the front-to-rear axis of the vehicle up to a maximum acceleration sensing level and providing a first acceleration signal indicative thereof, sensing vehicle acceleration in the offset direction at acceleration levels in excess of said maximum acceleration sensing level and providing a second acceleration signal indicative thereof, selecting one of the first acceleration signal and the second acceleration signal in response to the value of the first acceleration signal, and determining a rollover condition in response to the selected one of the acceleration signals and the sensed roll signal.
In accordance with yet another aspect of the present invention, a method detects a rollover condition of a vehicle comprising the steps of sensing vehicle roll and providing a roll signal having a characteristic indicative thereof, sensing vehicle acceleration in a direction offset from a front-to-rear axis of the vehicle and providing an acceleration signal indicative thereof, and determining the occurrence of a vehicle rollover condition in response to the roll signal indicating a vehicle rollover condition and the acceleration signal having a value between a first acceleration threshold and a second acceleration threshold.